Vascular neuroeffector mechanisms cannot be viewed in terms of synaptic function at non-vascular sites, nor can those in one type of vessel be directly related to another. The proposed research is an attempt using a multidisciplinary approach to quantitate mechanisms subserving the adrenergic transmitter process in the blood vessel, to delineate the basis of its variation in different vessels, and finally, to synthesize all this data to a composite picture and construct a model of the process in the vascular system. There are two specific objectives: firstly, to refine and extend our knowledge of the integrated neuroeffector process in the elastic vessel and secondly, the extend our investigation to other vessels of different size and function, including those with an internal diameter as small as 50 micra. The factors to be studied include those that influence the distribution and the effective concentration of the transmitter in the muscle-containing layer of the vessel wall and those that influence the magnitude and nature of the muscle response. A wide spectrum of physiological and biochemical methods will be applied to excised animal blood vessels. Since our objectives necessitate the use of small vessels, a number of microtechniques will be developed and employed.